长波长GaInNAs垂直腔面发射激光器

新出现的直接跃迁GaInNAs与具有高反射率的AlAs／GaAs分布布拉格反射镜相结合构成了GaAs基长波长(1．3—1．6μm)垂直腔面发射激光器(VCSEL)，将成为光纤通信、光互联和光信息处理等的关键元件。本文从材料的选取、外延技术和GaInNAs VCSEL国外和国内的发展状况等方面对长波长GaInNAs VCSEL进行了综合阐述。     

Microwave Dielectric Properties of ZnO-2TiO<Subscript>2</Subscript>-Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> Ceramics with BaCu (B<Subscript>2</Subscript>O<Subscript>5</Subscript>) Addition

The influence of BaCu(B₂O₅) (BCB) addition on the sintering temperature and microwave dielectric properties of ZnO-2TiO₂-Nb₂O₅ (ZTN) ceramic has been investigated using dilatometry, x-ray diffraction, scanning electron microscopy, and microwave dielectric measurements. A small amount of BCB addition to ZTN can lower the sintering temperature from 1100°C to 900°C. The reduced sintering temperature was attributed to the formation of the BCB liquid phase. The ZTN ceramics containing 3.0 wt.% BCB sintered at 900°C for 2 h have good microwave dielectric properties of Q × f = 19,002 GHz (at 6.48 GHz), ε _r = 45.8 and τ _f  = 23.2 ppm/°C, which suggests that the ceramics can be applied in multilayer microwave devices, provided that Ag compatibility exists.     

信号估计中的核回归方法

核回归方法是比较常用的一种非参数估计方法。讨论了核回归方法在一维信号估计中的理论与应用,实验比较了高斯核函数的平滑参数h及多项式阶数N对估计效果的影响。结果是在相同阶数N下,较小的h使所有的估计点都收敛到观察值,反之则是一个N阶多项式拟合。在相同h下,阶数N越大,误差越小,计算量也较大,但重构效果的提升并不明显。     

Analysis and design considerations of a load and line independent zero voltage switching full bridge DC/DC converter topology

The analysis and design of a zero voltage switching (ZVS) full bridge DC/DC power converter topology is presented in this paper. The converter topology presented here employs an asymmetrical auxiliary circuit consisting of a few passive components. With this auxiliary circuit, the full bridge converter can achieve ZVS independent of line and load conditions. The operating principle of the circuit is demonstrated, and the steady state analysis is performed. Based on the analysis, a criterion for optimal design is given. Experiment and simulation on a 350-400 V to 55 V, 500 W prototype converter operated at 100 kHz verify the design and show an overall efficiency of greater than 97% at full load.     

Design and fabrication of waveguide-based chip-to-chip optical interconnection network on printed circuit boards

A waveguide-based chip-to-chip optical interconnection network on printed circuit board (PCB) was designed and fabricated, and experiments confirmed that the data rate in each channel could reach above 3.125 Gbit/s and the bit error rate (BER) could be up to 1.27×10-18, which would be a good solution to solve the communication bottlenecks between high-speed very large scale integration chips. Besides, the whole design and fabrication of optical interconnection network on printed circuit board has the advantages of high reliable, low cost and ease of manufacture.     

水下爆炸对水下目标的毁伤试验研究

为研究水下爆炸对蛙人的毁伤效果,进行了GUHL-1的水下爆炸试验,得到不同爆距处冲击波峰值压力。通过计算获得GUHL-1炸药水中爆炸自由场冲击波压力峰值和爆距的关系。同时对几种反蛙人武器系统的毁伤效果进行了分析,为今后反蛙人武器系统的设计提供参考。     

半捷联惯导系统轴向角度安装误差分析与补偿

针对半捷联惯性测量系统中轴向角度安装误差影响系统姿态测量精度的问题,分析了轴向角度安装误差的来源、产生机理及其对姿态测量精度的影响规律,并从理论上推导了其数学表达式。在此基础上,提出了轴向角度安装误差的分级补偿方法。该方法的核心思想是,根据轴向角度安装误差产生的原理和作用机理不同,依次对其补偿。地面实测试验表明,对轴向角度安装误差的补偿方法是正确和有效的,利用该补偿方法可以将轴向角度安装误差引起的周期性姿态测量误差由0.32°减小到0.05°以内,减小幅度达1个数量级,显著地提高了系统的解算精度。     

某火箭炮底架结构的拓扑优化设计

以某发射装置底架为研究对象,在优化软件Hyper Mesh中建立其有限元模型,并确定底架在4个典型工况下的载荷及约束条件。在Optistruct模块下,通过变密度法对底架在4个典型工况下进行两次拓扑优化,达到了轻量化目的。对模型进行了有限元划分,将其简化为2D板壳单元,仍然取4个极限工况对模型进行静力分析,验证底架变形量与最大应力是否均在许用范围之内,实现了对底架的全新结构设计。     

基于近场声全息的水下航行器噪声源定位方法

以水下航行器的噪声源定位为研究背景,综合论述了基于空间傅里叶变换的近场声全息技术的研究现状,重点研究了算法误差、重建稳定性和滤波方法,分析了近场声全息技术目前仍需解决的问题,并结合Patch近场声全息、矢量水听器等新技术给出了相应的建议,旨在为近场声全息应用到水下噪声源定位提供依据。     

轴对称侵彻体阻力模型

本文建立了一个拟球形弹丸侵彻半无限靶的阻力模型。其中考虑靶材的离心效应,修正了Goodier侵彻理论,并证明了解的正确性。可用于研究高、低弹速的侵彻问题,并可用以解释和计算侵彻过程中的弹靶分离现象。